The tunica media serves what function in arteries?

The tunica media serves what function in arteries?

• A. Contract and dilate to change diameter
• B. Form the external protective layer
• C. Store blood
• D. Produce enzymes

Answer: (A)

The tunica media is the muscular middle layer of arteries, and its job is to adjust the vessel’s diameter through smooth muscle contraction and relaxation. When the smooth muscle contracts, the artery narrows (vasoconstriction), which increases resistance and reduces flow to certain areas. When the muscle relaxes, the artery widens (vasodilation), lowering resistance and allowing more blood to pass. This ability to change radius is essential for directing blood where it’s needed and for helping maintain overall blood pressure. Additionally, in large arteries the tunica media contains elastic fibers that support elastic recoil, helping the vessel maintain pressure between heartbeats. The other options describe functions of different structures or are not the main role of the tunica media: the outer protective layer is the tunica adventitia; storing blood is a function more associated with veins; producing enzymes is not the primary function of the tunica media in arteries.

The tunica media is the muscular middle layer of arteries, and its job is to adjust the vessel’s diameter through smooth muscle contraction and relaxation. When the smooth muscle contracts, the artery narrows (vasoconstriction), which increases resistance and reduces flow to certain areas. When the muscle relaxes, the artery widens (vasodilation), lowering resistance and allowing more blood to pass. This ability to change radius is essential for directing blood where it’s needed and for helping maintain overall blood pressure.

Additionally, in large arteries the tunica media contains elastic fibers that support elastic recoil, helping the vessel maintain pressure between heartbeats. The other options describe functions of different structures or are not the main role of the tunica media: the outer protective layer is the tunica adventitia; storing blood is a function more associated with veins; producing enzymes is not the primary function of the tunica media in arteries.